Find the numbers.

Question

The sum of two numbers is 20. The difference of two numbers is -4. Find the numbers.

Answer 1

Let the numbers be x and y.

The sum of two numbers is 20

x + y  =  20 ------------> (1)

The difference of two numbers is -4

x - y  =  - 4 ------------> (1)

Add Equations (1) and (2)

     x + y  =  20

     x - y  =  - 4

------------------------

2x  =  16

x  =  16/2

x  =  8

Substitute x = 8 in Eq (1)

8 + y  =  20

y  =  20 - 8

y  =  12

Answer :

The solutions are x = 8 and y  =  12.